oil does make a difference

7/27/2019 Oil Does Make a Difference

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Four different oils were chosen for thetest. The oils tested were: 1)Pennzoil Two-Cycle Air-Cooled

Engine Oil; 2) Pennzoil Premium Out-board and Multi-purpose Two Cycle Oil;3) A conventional petroleum two-cycleoil; and 4) A two-cycle synthetic oil.

Each oil was color coded for identifica-tion and assigned to a particular engine(see Table 1 on next page.) To ensure a

blind test, the technicians operating thetest stand were unaware of which productwas used in each engine.

Pennzoil Two-Cycle Air-Cooled En-gine Oil is a low ash, two-cycle oil meetingAPI TC requirements. API TC is theAmerican Petroleum Institute standard forTwo-Cycle air cooled engines. Detergentadditives incorporated into this producthelp protect against high temperature pis-

When Pennzoil-Quaker State Company decided to upgrade its popular Pennzoil

Outboard and Multi-Purpose Two-Cycle Oil formulation, they felt it was necessary tolook at all niche markets the product was used in to be sure the changes would bebeneficial for the end user. Because of the popularity of Pennzoil products in the

sport aviation market, it was imperative that the product upgrade be tested in two-cycle sport aviation engines. So, they teamed up with Rotax engine experts, Lock-

wood Aviation in Sebring, Florida, to design a test that would assure the new product

would continue to protect these engines.

by Mike MaddoxNational ManagerTechnical Service

Pennzoil-Quaker State ProductsCompany

Reprinted by permission fromEAA EXPERIMENTER


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ton ring sticking. This product has gainedwide popularity over the last ten years insport aviation two-cycle engines and isused in both air- and water-cooled two-cy-cle sport aviation engines with greatsuccess.

Pennzoil Premium Outboard andMulti-purpose Two-Cycle Oil is a Na-tional Marine Manufacturers Association

(NMMA) TC-W3 certified two-cycle oil(see sidebar How Two-Cycle OilsWork) that also meets API TC. Thisproduct incorporates ashless dispersantchemistry. This product is also used inboth air- and water-cooled two-cycle sport

aviation engines and is now gaining popu-larity in Rotax 618 engine models, whichare equipped with Rotax Adjustable Vari-able Exhaust (RAVE) valves.

In this test, the Pennzoil oils were com-pared to typical pe troleum-based andsynthetic low-ash two-stroke oils.

It is worthy to note that many pilots us-ing synthetic oil may mix at a higher(leaner) fuel/oil ratio than the engine manu-facturer may specify. Synthetic oils tend towork well against deposit formation at

these higher ratios, however engine manu-

facturers generally state that the higher(leaner) oil ratio may not provide enoughresidual protection from corrosion duringextended storage conditions. Therefore, alloils run in this test were run at the manufac-turers recommended fuel/oil ratio of 50:1.

The Test

Four new Rotax 503 two-cylinder fan-cooled engines were purchased andutilized since it is one of the most popularengines in this market. Each engine useda premix oiling system instead of the oil

injection option. The engines were fueledwith premium unleaded gasoline that wasmixed with the test oils at the engine man-ufacturers recommended ratio of 50:1.The engines were set up identically toachieve 6300 rpm at full throttle. After aone hour prescribed break-in cycle, theengines were run under strenuous one-hour cycles simulating a typical flightroutine i.e., full power takeoff, cruise,descent, and idle conditions (See Table 2on this page).

Table 1

Oil Code Product Description

Blue Pennzoil 2-Cycle Air-Cooled Engine Oil Low ash API TCRed Pennzoil Outboard and Multipurpose 2-Cycle Oil Ashless TC-W3 / API TCPurple Conventional Petroleum 2 Cycle Oil Low ash API TCYellow 2-Cycle Synthetic Oil Low ash API TC

A. The grueling test stand. Four Rotax 503 engineswere purchased new for the Pennzoil test andmounted on this flatbed trailer. Each engine wasassigned a specific test oil and all were run concur-rently prior to engine teardown and evaluation.Lockwood Aviation President Phil Lockwood, ob-serving one of the test runs here, acknowledgedthat running the test was definitely hard o n theears and the tires on that side of the flatbed

trailer. Needless to say, they were also the objectof quite a few stares each time they refilled thetanks at local gas stations.

B. After 280 hours of run time, the engines weretorn down and inspected by independent certifiedengine raters using Coordinating Research Councilindustry standards. Here, Mike Maddox, NationalManager of Technical Service for Pennzoil, in theforeground, records measurements taken by Lock-wood Aviations Rotax Repair Specialist Kerry Yunk

C. A control panel allowed the operator to coordi-nate identical operating conditions on all fourengines simultaneously.

Table 2

Operating Condition Time (minutes)Idle 5Take Off - Full Power 4

Cruise - 5,800 rpm 47Descent and landing - 4,000 rpm 4

A BC


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After 280 grueling hours, the engineswere disassembled, rated for deposit ac-cumulation, piston ring sticking andmeasured for wear. Independent certifiedengine raters used Coordinating ResearchCouncil (CRC) industry standards toevaluate each engine in the areas of pis-

ton, ring and exhaust port depositaccumulation, piston ring sticking, pistonscuffing, and ring and cylinder wear.Keeping these critical areas clean and freeof deposits and wear helps ensure longerengine life.

The rating standards are based on ascale from 1 to 10. The higher the rating,the better the evaluation or performance ofthe lubricant in the specific area rated.

The piston rings were rated as to thestate of sticking and the degree of circum-

ference around the piston that they werestuck. Deposits were evaluated by volumeand appearance, ranging from 10 (clean-absence of deposits) to 0.0 (maximumdeposits those deposits which take upALL of the available space between mov-ing parts and display rubbed or polished

characteristics).Resistance against cylinder head, piston

and ring land deposits is very important inengines. Piston rings help remove heatfrom the piston and transfer it to the coolercylinder walls, as well as provide sealingbetween the combustion chamber andcrankcase. If deposits become too heavyand piston rings become stuck in theirgrooves, then premature wear and damagewill occur due to the rings inability toproperly seal the combustion chamber and

transfer heat. Excessive cylinder head de-posits increase the octane requirement ofthe engine and may also cause pre-igni-tion and detonation, leading to enginedamage.

Graph 1 shows that Pennzoil Pre-mium Outboard & Multi-purposeTwo-Cycle Oil (identified as the red oil)

performed exceptionally well, particularlyin the areas of combustion chamber clean-liness and piston crown deposits.Pennzoil Two-Cycle Air-Cooled En-gine Oil (blue oil) performedexceptionally well in the areas of resis-tance to piston ring sticking and pistonring land deposits.

Graph 2 evaluates piston skirt de-posits on both the thrust and anti-thrustsides of the piston. The thrust side of thepiston is the side that tends to bear mostheavily against the cylinder wall duringthe power stroke. The anti-thrust side of

the piston tends to bear most heavilyagainst the cylinder wall during the com-pression st roke. When the transitionoccurs from the compression stroke to thepower stroke, the connecting rod anglewill change. This change causes a suddenshift of the side thrust on the piston. Ifthere is any appreciable piston wear or de-posits, contact of the piston skirt with thecylinder wall can occur.

Exhaust Port Deposits

The photographs on the next pages

show the deposits inside of the exhaustpor t. Depos it buildup in the exhaustport can affect the scavenging proper-ties of the two-cycle engine. Also, inRotax engines that use RAVE valves,resistance of an oil to deposit buildup iscritical for proper operation of the vari-able exhaust valves.

The blue oil (Pennzoil 2-Cycle Air-Cooled Engine Oil) performed extremelywell as did the red oil (Pennzoil Pre-mi um Outboard And Multi-PurposeTwo-Cycle Oil).

The purple oil (conventional mineral)

and the yellow oil (synthetic) formed sig-nificantly more deposits in the exhaust portarea. However, real world tests usingsynthetic oils at typical leaner mixturesshow far less deposits.

If we had any doubts, these tests con-firmed that oil obviously does make adifference in the performance of a sport avi-ation engine! Pennzoil was proud to confirmthat its line of two- cycle oils continue toprovide the highest degree of performancein this demanding application.

Graph 1

Graph 2


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Blue

Blue

Blue

Red

Red

Red

Purple

Purple

Purple

Yellow

Yellow

Yellow


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Blue Red

Purple Yellow

Pennzoil Premium Outboard and Multi Purpose 2 Cycle Oil Pennzoil 2-Cycle Air Cooled Engine Oil


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T

here are several oils for an ultralight pilot to se-lect from, and everybody has their favorite.Others are confused about claims as to which

one they should use and why. How about oil injectedversus the common fuel and oil pre-mix? What thedifference between an oil formulate for water-cooledengines and an oil made for air-cooled engines?

To understand how two-cycle oils work in your en-gine, we need to cover some basic training on engineoperating conditions and oil formulation.

Outboard engines are characterized by their con-stant speed, high output operation. They are usuallyset at a desired high speed and continue at thatspeed until the destination is reached and then throt-tled down. Also, they are constantly cooled withfresh, cool, non-recirculated water. Chain saws, onthe other hand, are a high action operation. Theyare constantly started and stopped, used for shortperiods and frequent overloads are its hard place inlife. Additionally they have smaller displacementsthan outboards and are air-cooled. By understand-ing how the operation of an engine can affect the oilused and how an oil can affect the engine, we canbetter appreciate the difference between a water-cooled two-cycle oil and one formulated for anair-cooled two-cycle engine.

Water-cooled two-cycle engine oils require higherlevels of a heavy oil to prevent piston and cylinder wallscuffing. Because of their high average piston temper-ature, lighter oils evaporate too quickly from thepiston cylinder contact area. The heavy base oil,which vaporizes at very high temperatures, resistsevaporation and remains in place to provide lubrica-tion to the piston and cylinder. Air-cooled oilformulations must have much lower levels of theheavy base oil than water-cooled engine oils. Theseoils require only a small amount of heavy oil to pro-vide protection against piston scuffing and seizure atpeak temperatures. Heavy levels of heavy base oils inan oil formulated for air-cooled engines can cause en-gines deposits. These deposits form as a result ofincomplete burning of the heavy oil. The deposits cancause piston ring sticking and can eventually plug ordisrupt the flow of the exhaust system, resulting in

power loss and possible engine damage. Detergentadditives should not be used in water-cooled two-cy-cle oil formulations. When burned with the fuel,detergents can produce an ash deposit in the cylin-ders. This ash deposit can possibly foul spark plugs,form exhaust port deposits which cause loss of power,and possibly create cylinder hot spots that can causedestructive pre-ignition.

On the other hand, the only way to protect air-cooled two-cycle engines against piston ring stickingat their high peak temperatures is to include some de-tergent additives in the oil formulation. Detergents

provide high temperature deposit control not availablefrom other additives used in the oil. However, in theair-cooled engine, any ash deposits that could form

from the detergents are dislodged by engine vibrationand exhausted from the engine.

Now is a good time for a lesson on ash. Ash is thenon-combustible residue of a lubrication oil or fuel.Detergent additives contain metallic derivatives, suchas calcium, barium and magnesium sulfonates thatare common sources of ash. Ash deposits can impairengine efficiency and power. But, detergents are animportant component of engine oil that help controlvarnish deposits, piston ring deposits and rust (yes,rust) by keeping insoluble combustion particles fromadhering to metal surfaces. In some cases, detergentsneutralize acids formed from combustion of the fuelmixture. Ash deposits may have a grayish color,

whereas carbon residue is usually black and sooty.Carbon residue, on the other hand, is different

from ash. Carbon residue is formed from unburnedand partially burned fuel, and from burning of thecrankcase lubricant. Water from condensation ofcombustion products along with carbon residue fromfuel contribute to engine piston deposits. Carbon de-posits are normally black and have a sootyappearance.

Oils formulated for outboard engines require alarge amount of antioxidant and dispersant additivesto control deposit formation since these oils do notcontain detergents. Outboard oils also contain a largeamount of rust inhibitors because an outboard en-gines continuous contact with water makes rustprevention an important requirement. Air-cooled oilscontain lower amounts of antioxidants and disper-sants, since the detergent additives do most of thework of preventing deposit accumulation. These oilsalso contain rust inhibitor additives to protect againstrust that can form from water that enters the enginedue to condensation.

So, how do some oils claim to be multi-purposeor formulated for water and air-cooled engines?These oils have usually been formulated to meet theNational Marine Manufacturers Association(NMMA) TC-WII or TC-W3 specification. These

specifications require the oils be tested under rigor-ous test conditions. An air-cooled engine test is partof these requirements. Therefore, a manufacturercan claim multi-purpose applications. Althoughthese oils have been tested in an air-cooled engineand will lubricate an air-cooled engine, an oil formu-lated specifically for air-cooled engine use may bethe best choice for your engine.

Just what oil does Rotax recommend for their two-cycle engines? Rotax recommends using an oilmeeting American Petroleum Institute (API) Service

Classification TC. API TC is a designation for high per-formance two-cycle engines (typically 50 to 500 cc)excluding outboard engines. This performance ratingis determined by engine tests that evaluate (1) anti-scuff characteristics, (2) piston ring sticking and enginecleanliness, and (3) pre-ignition. In the TC category, a50 cc and a 350 cc Yamaha engine are used to evalu-ate the oil.

Engines that require the fuel and oil to be pre-mixed should use a two percent (50:1) concentrationof oil in the fuel. It is very important that the fuel/oilmix is correct. In other words, dont add too muchor too little oil to the fuel. If a little does good, moreoil added to the fuel doesnt necessarily do better.

In fact, too much oil will lead to excessive depositsand could also cause excessive exhaust smoke andspark plug fouling. Not enough oil can lead to pis-ton skirt and cylinder wall scuffing and eventualengine damage.

Gasoline containing alcohol (ethanol and/ormethanol) should not be used unless permitted by theengine manufacturer. Alcohol-containing fuels canabsorb water and separate from the gasoline. Addi-tionally, the alcohol may not be compatible with somefuel system components, such as plastic and rubbercompounds.

Rotax also recommends de-carboning the en-gine after every 50 hours of operation. This procedureis designed to remove excessive piston deposits tocheck for possible stuck piston rings. Rotax allows upto 0.040 inches of soot and carbon buildup on the pis-ton crown before removal of the carbon is required.Not only does Rotax recommend an API TC oil for the447 and 503 air-cooled engines, but also for the 532and 582 engines run at internal temperatures similarto the air-cooled Rotax engines, as evidenced by theiruse of the same spark plug.

Special precautions should be taken when switch-ing oils, even between the same brands. Because ofthe special formulation of air-cooled engine oil, theseoils generally are not compatible with water-cooled

engine oils. Caution should be exercised to ensurethat these products are not mixed together. Specialprecautions should be taken when changing from aproduct designed primarily for water-cooled enginesto an air-cooled product, particularly in oil injectionsystems where the undiluted oils would be mixed to-gether. It is recommended that the oil reservoir andlines be drained when changing to another formula-tion. In applications where the oil is premixed withthe fuel, it is recommended the fuel tank(s) be drainedand filters changed.by Charles Kudolis

(Excerpted fromEXPERIMENTER,

April, 1994)

oil does make a difference

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